1. Field of the Invention
The present invention relates to a semiconductor device, an imaging device, and a semiconductor device manufacturing method.
2. Description of the Related Art
As methods of electrically connecting wafers in which semiconductor devices are provided to each other, active research and development is being carried out on methods of heating and pressing the wafers using a solder bump or a metal bump to connect the wafers and methods of connecting the wafers by heating adhesion using a resin, such as an anisotropic conductive adhesive material. In the research and development, a wafer stacking technology using a photosensitive resin is also being examined (e.g., see “Uncontrollable movement toward 3D stacking—Cutting-edge technologies and industry trends of 2.5D/3D stacked devices for practical application—Open research meeting document of 3rd system integration packaging technology research meeting, Oct. 25, 2011, p. 77 to 90”).
The wafer stacking technology using a photosensitive resin is as follows. In other words, a resin film is formed by spin-coating a liquid photosensitive resin or vacuum-laminating a photosensitive resin in the form of a sheet on a bonding surface of a wafer to be stacked. To bond wafers together, a resin film is heated not to a fully cured state but to a semi-cured state, a pattern is exposed and developed using a photo mask, and the resin film is subjected to post baking. An electrode for connection is formed using a plating method, a sputtering method, a vapor deposition method, or the like. After that, the electrode is flattened together with the resin film by chemical mechanical polishing (CMP), single point grinding, or the like, and heated and pressed to bond the wafers together.